The present invention relates to switch structures and electronic/electric component part installing structures suited for application to various electronic equipment, such as electronic musical instruments, and electronic musical instruments including such switch structures or electronic/electric component part installing structures.
The various conventionally-known electronic equipment, such as electronic keyboard musical instruments, includes various operating switches provided on an operation panel. Among examples of such switches are switch structures disclosed in Japanese Patent Application Laid-open Publication No. HEI-11-39994 (hereinafter referred to as “patent literature 1”) and Japanese Patent No. 2650179 (hereinafter referred to as “patent literature 2”). The switch structure disclosed in patent literature 1 includes a plate-shaped operation panel having holes through which controls (or operators) are partly exposed out of the holes, a circuit board disposed under the operation panel, fixed contacts provided on the circuit board, the controls each vertically movably mounted to the underside of the operation panel via a flexible hinge portion, actuators each having a projecting shape and provided on the underside of a corresponding one of the controls; contact rubber members each provided on the circuit board and formed of resilient resin for being depressed by a corresponding one of the actuators; and movable contacts each provided on the underside of a corresponding one of the contact rubber members. The operation panel having the controls mounted to its underside and the circuit board having the contact rubber members on its topside are fixed in spaced apart relation to each other via spacers. As any one of the controls projecting out of the holes is depressed by a user's finger or the like, the contact rubber member corresponding to the depressed control is depressed and resiliently deformed by the actuator of the control. Thus, the movable contact of the contact rubber member contacts a corresponding one of the fixed contacts on the circuit board, so that a corresponding switch is turned on.
In the switch structure disclosed in patent literature 1, the actuator of each of the controls is disposed over the corresponding contact rubber member provided on the circuit board, and the contact rubber member is constantly slightly pressed by the control against the circuit board. Because the control is vertically movably provided via the flexible hinge portion, the contact rubber member and the control is slightly movable relative to the circuit board and operation panel rather than being completely fixed to the circuit board and operation panel. However, in a case where the switch structure disclosed in patent literature 1 is provided in an electronic keyboard instrument that audibly generates sounds through a speaker or the like, a casing of the electronic keyboard instrument would slightly vibrate depending on sounds generated. In such a case, vibrating sound (so-called RUB & BUZZ) may undesirably occur in the controls and contact rubber members due to the slight vibration propagating from the casing to the circuit board and operation panel. As one approach for reducing the vibrating sound, it may be conceivable to apply pre-tension to the hinge portions so that the contact rubber members are mounted on the circuit board in a slightly pressed state. With such an approach, however, deformation may undesirably occur in the contact rubber members, preventing appropriate ON/OFF operation of the contacts.
Further, the switch structure disclosed in patent literature 1, the controls partly exposed out of the holes and the contact rubber members to be pressed by the controls are constructed as separate parts, which would thus result in a great number of necessary component parts of the switch structure and prevent simplification of the switch structure. In addition, the great number of component parts would require much time and labor in assembly work and can prevent simplification of manufacturing steps of the switch structure.
Further, the switch structure disclosed in patent literature 2 is a key switch structure of an electronic keyboard instrument which includes: a keyboard having a plurality of keys, actuators each having a projecting shape and provided on the underside of a corresponding one of the keys; and a contact rubber member formed of a resilient material, such as rubber, and disposed between the actuators and a circuit board having fixed contacts disposed under the keyboard. The contact rubber member includes a plate-shaped base section provided on the circuit board, upwardly-convexed cup portions provided on the base section and spaced from each other at predetermined intervals, and movable contacts each provided on the underside (inner bottom surface) of a corresponding one of the cup portions. Further, small mounting projections are provided on the base section of the contact rubber member and fixedly inserted in corresponding small fixing holes formed in the circuit board.
In the switch structure disclosed in patent literature 2, the contact rubber member is fixedly mounted on the circuit board by means of the small mounting projections, and the contact rubber member is pressed against the circuit board via the actuator of the key abutted against the upper surface of the cup portion. Thus, even if the casing of the electronic keyboard instrument slightly vibrates due to sound audibly generated through a speaker and propagates form the casing to the circuit board and operation panel, it is possible to suppress, to some degree, vibrating sound occurring in the contact rubber member. However, with the switch structure disclosed in patent literature 2, where the entire base section including portions located between the adjoining cup portions is disposed in face contact with the upper surface of the circuit board, vibrating sound (Rub & Buzz) can occur between the base section and the circuit board due to the slight vibration.
Further, with the switch structure disclosed in patent literature 2, the small mounting projections, provided on the contact rubber member as a structure for fixing the rubber member, can suppress, to some degree, vibrating sound of the contact rubber member. However, because the contact rubber member includes a rubber sheet of a thin plate shape having not only a multiplicity of contacts integrally formed thereon but also the above-mentioned small mounting projections formed thereon at predetermined intervals, the contact rubber member would undesirably become complex in shape. Besides, because operation for fixedly inserting the small mounting projections into the small holes of the circuit board, much time and labor would be required for assembling the switch structure.